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Matching Sides

Part of the Congruence & Proof section of Coddy's Geometry journey. Lesson 7 of 63.

Matching corners give matching sides. In △ABC ≅ △DEF, side AB joins the first and second corners, so it matches DE, which joins the first and second corners of the other triangle. In the same way BC matches EF, and CA matches FD.

$Triangles ABC and DEF with matching sides marked with one, two and three ticks$

Congruent triangles have their matching sides equal: AB = DE, BC = EF and CA = FD. To find the side matching any side, write down the positions of its two letters and read the letters in those positions from the other name.

Challenge

You are given △JKL ≅ △XYZ. Tap the side of △XYZ that matches JL, then press Check.

Try it yourself

$Find the right part on the figure$

Find the right part on the figure

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Congruence & Proof

2Congruent Triangles

Same Size, Same ShapeMatching SidesMatching Angles What Congruence Gives Recap: Matching Parts

5ASA and AAS

The Side Between The ASA Rule The AAS Rule ASA or AAS?Recap: ASA and AAS

8Proofs with Vertical Angles

Vertical Angles in Proofs The Bowtie Bowtie with ASA Linear Pairs in Proofs Recap: Vertical Angles

11Similarity Proofs

AA Similarity Two Right Triangles SSS Similarity SAS Similarity Similar, Then Find Recap: Similarity